This month AEi Systems presented two papers (abstracts below) at the Aerospace Space Power
Workshop in Manhattan Beach, CA:
“Lessons Learned from WCCA” and
“A Simple Method for Stabilizing Regulators”
Copies of the presentations are available for download at
The results of an ongoing AEi Systems survey covering
Voltage Regulator Testing and Worst Case Analysis have been
Regulator Stability Survey. You too can take the survey at
http://aeng.com/regulator_survey.htm. As a “thank you” for filling out this survey
completely, AEi Systems will donate $5.00 per survey to the American Cancer Society.
High Temp Component Aging in Power Converters
Stability Assessment of Fixed Regulators
Boeing Recognizes AEi Systems Achievements on GPSIIF Clock WCCA
Why do a Worst Case Analysis?
If you have ever wondered why you need to do a WCCA, this paper will outline the
rationale and cost saving upsides.
AEi Systems offers a full range of Analog Engineering Services.
We have a hard-earned reputation for delivering ahead of schedule, being under budget and
meeting all specifications.
But most importantly, we are passionate about getting it right.
We help our customers achieve GREAT results, providing LONG-TERM benefits to their product lines.
We can work with you too, interactively, keeping you in the loop as the analysis proceeds and offering
design fixes where appropriate. Issues are identified and solved in a timely fashion, saving both time
and money and allowing you to more efficiently deploy your precious design resources.
AEi Systems Services:
Worst Case Circuit Analysis for Power, RF, Linear and Digital Systems
• WCCA Plan Development and WCCA Bidding
• Electrical SDRLs: MTBF/Reliability, FMECA, Stress & Derating, and Radiation Analysis
Signal Integrity Analysis: Decoupling, Noise, Crosstalk, Compatibility!
• Component and Circuit Test and Characterization
• Hardware/Failure Analysis & Troubleshooting
AEi Systems achieves
• We have brought together top engineers with focused backgrounds
in reliability, design and test
• We dig deeper to get it right, because we believe it's
simply unacceptable to be complacent
• We believe in making sure things work in tough places for
a long time
AEi Systems is
a unique resource:
• We do it faster, better and at a lower cost than in-house
• We help our customers meet their deadlines, yet we never
How can we help you? Contact us for more specific information or a no-obligation
“Lessons Learned from WCCA” Synopsis –
This presentation discusses the general problems associated with analysis methods and practices
including issues with the rigorousness, mathematical approaches, formats, modeling, personnel/engineering
talent employed, and proper review process. Conclusions on how to improve the quality of the WCCA are
presented. The presentation also focuses on lessons learned from actual worst case analyses. Several
examples are shown detailing the problems uncovered by WCCA. Topics include stability analysis, tolerance
stack-up, and the limitations of testing as an alternative to WCCA.
“A Simple Method for Stabilizing Regulators” Synopsis -
Engineers have trouble analyzing and achieving stability for linear regulators. Given how little
stability data are published by the manufacturers, this is not surprising. In most linear regulators,
the output capacitors’ ESR provides the control loop zero, stabilizing the regulator. The datasheet
generally offers little information regarding the stability of the regulator as a function of the load
current, output capacitance and output capacitor ESR. Additionally, capacitor ESR is an uncontrolled
parameter and in many cases the load impedance is a complex set of capacitors, beads, and IC loading.
This article discusses a simple measurement that reveals the capacitor ESR required to achieve a particular
phase margin for any output capacitance value. That is, if you know the output capacitance and output load
current you can tell what value of ESR will lead to a configuration with the desired phase margin.